Stability of unused reconstituted bortezomib in original manufacturer vials.

UNLABELLED BACKGROUND. Bortezomib is a modified dipeptidyl boronic acid analogue used to treat multiple myeloma, mantle cell lymphoma, and, more recently, renal transplantation graft rejection. As per manufacturer recommendations, bortezomib is to be administered within 8 h of preparation or may be stored for up to 8 h in the vial or a syringe following reconstitution. Preserving unused reconstituted bortezomib beyond these 8 h may allow for cost savings. This study aims to examine the stability of unused reconstituted bortezomib when stored at 4°C for up to 15 days. METHODS Using an LC-MS/MS assay, the concentration of reconstituted bortezomib was measured at predetermined time points following storage at 4°C in the manufacturer vial. Percent bortezomib remaining at a time point was calculated versus initial bortezomib concentration. RESULTS The concentrations of bortezomib were found to be 51.93 ng/mL±4.60 after 1 day of storage, 57.40 ng/mL±4.77 after 8 days of storage, and 49.43 ng/mL±2.85 after 15 days of storage. The percent of bortezomib remaining was 110.53% and 95.19% after 8 days and 15 days, respectively. CONCLUSION Unused reconstituted bortezomib is stable for up to 15 days stored at 4°C in the original manufacturer vial. Such use of bortezomib may improve cost efficiency by reducing bortezomib waste.